UNIVERSITY     OF     CALIFORNIA       AGRICULTURAL   EXPERIMENT  STATION 

BENJ.     IDE     WHEELER,     PRESIDENT 

COLLEGE    OF    AGRICULTURE  thomas   forsyth    hunt,  dean  and  director 

H.       E.      VAN      NORMAN,      VlCE-Ol  R  ECTOR      AND       DEAN 
BERKELEY  UNIVERSITY     FARM    SCHOOL 

CIRCULAR  No.  146 
(January,  1916) 


JELLIES  AND  MARMALADES  FROM 
CITRUS  FRUITS 

By  W.  V.  CRUESS 


Investigations  of  the  by-products  of  the  citrus  industry  by  the 
Division  of  Viticulture  during  the  past  two  years  have  yielded  some 
results  regarding  the  possibilities  of  jelly  making  that  appear  to  be 
of  value. 

They  have  shown,  what  has  been  doubted  by  some,  that  very 
attractive  and  palatable  jellies  and  marmalades  can  be  made  from 
Californian  oranges,  lemons,  and  pomelos.  They  have  shown  further 
that  these  fruits  contain  large  amounts  of  pectin  which  can  be  used 
in  combination  with  such  fruits  as  strawberries,  cherries,  and  peaches, 
containing  little  or  no  pectin,  to  produce  jellies  with  the  characters 
and  flavors  of  these  latter  fruits.  No  outside  jelling  material  such 
as  gelatin  is  needed  in  either  case.  The  interest  in  this  subject  is 
evidenced  by  the  number  of  letters  received  asking  for  information 
regarding  citrus  jellies  and  marmalades  and  indicates  that  these 
products  may  furnish  an  outlet  for  some  of  our  citrus  crop. 

The  chief  aim  of  this  publication  is  to  furnish  information  for 
home  use,  but  the  principles  discussed  apply  equally  to  production  on 
an  industrial  scale. 

Pectin. — Pectin  is  the  essential  constituent  of  jellies  and  mar- 
malades because  its  presence  is  necessary  to  give  the  desired  consistency. 
Citrus  fruits  are  very  rich  in  this  substance.  It  is  most  abundant 
in  the  white  inner  portion  of  the  skin,  but  occurs  also  in  the  pulp  of 
the  fruit. 

Extraction  of  Pectin. — The  pectin  is  held  firmly  by  the  tissues  of 
the  fruit  and  is  not  very  soluble  in  cold  water.  By  heating  the  fruit 
in  the  juice  or  in  water,  the  tissues  are  softened  and  the  pectin  dissolved 
by  the  liquid.  The  pectin  solution  thus  obtained  serves  as  the  basis  for 
jelly  or  marmalade. 


The  whole  fruit  is  used  and  is  first  eut  into  pieces  about  one- 
fourth  of  an  inch  thick.  If  cut  too  fine,  the  fruit  in  cooking  becomes 
" mushy"  and  the  pectin  solution  very  cloudy;  if  too  coarse,  the 
pectin  is  imperfectly  extracted.  The  liquid  should  cover  the  fruit 
and  boil  slowly,  the  volume  of  water  being  kept  constant  by  additions 
of  water  when  necessary.  Rapid  and  too  prolonged  boiling  softens 
and  breaks  up  the  fruit  and  gives  a  muddy  liquor.  About  one  hour's 
slow  boiling  has  given  very  satisfactory  results.  At  the  end  of  this 
time  the  liquid  contains  the  pectin  and  should  be  clear  and  of  a  more 
or  less  gummy  consistency.  It  must  be  separated  from  the  fruit  while 
still  hot  to  avoid  the  necessity  of  too  much  pressing.  Most  of  the 
pectin  solution  may  be  strained  off  through  a  coarse  mesh  bag  (e.g., 
cheesecloth)  without  pressure;  the  remaining  liquid  may  be  extracted 
by  gentle  pressure.    The  press  liquor  may  be  kept  separate. 

Clearing  the  Pectin  Solution. — Jelly  is  most  attractive  if  bright. 
The  clearing  must  be  done  before  sugar  is  added.  The  most  simple  and 
effective  method  found  so  far  is  to  allow  the  pectin  solution  to  stand 
twenty-four  hours  to  settle.  The  clear  liquid  can  then  be  decanted 
or  siphoned  off  and  used  without  further  clarification.  The  sediment 
can  be  strained  through  a  heavy  felt  or  flannel  jelly  bag.  Fruit  jars 
or  bottles  are  suitable  containers  for  the  liquid  during  the  settling 
process.     Tall  earthenware  crocks  may  be  used  for  larger  quantities. 

If  the  boiling  of  the  fruit  and  draining  off  of  the  pectin  solution 
have  been  carefully  done,  the  liquid  obtained  will  often  be  clear  and 
no  settling  necessary.  If  large  jelly  bags  are  available,  the  hot  pectin 
solution  may  be  filtered  through  them  to  give  a  clear  liquid  and  the 
settling  process  dispensed  with. 

Acidity  of  Pectin  Solution. — Besides  pectin,  acid  is  also  necessary 
for  jelling.  Ripe  oranges  and  grape  fruit  do  not  contain  quite  enough 
of  this  material  to  give  a  good  jelly  in  all  cases.  This  deficiency  is  most 
conveniently  made  up  by  the  addition  of  lemons.  Four  to  six  lemons 
should  be  cut  up  with  each  dozen  oranges  or  pomelos  and  boiled  with 
them  during  the  pectin  extraction.  Tests  have  shown  that  the  pectin 
solution  should  contain  at  least  .8  to  1  per  cent  of  citric  acid  to 
give  the  best  results.  The  above  proportion  of  lemons  will  give  this 
amount  of  acid. 

Sugar. — In  addition  to  pectin  and  acid,  sugar  is  necessary.  Cane 
sugar  and  beet  sugar  are  equally  good  for  this  purpose.  They  are 
the  same  chemically  and  the  prejudice  against  beet  sugar  seems  un- 
warranted. Sugar  causes  the  pectin  to  jell  and  preserves  the  product. 
The  amount  of  sugar-  necessary  to  cause  jelling  will  vary  inversely  with 


the  amount  of  pectin  present;  that  is,  the  richer  the  pectin  content 
of  the  solution,  the  less  sugar  is  required  to  give  a  jelly.  A  jelly 
may  be  obtained  with  50  per  cent  of  sugar  or  less  where  there  is  a 
large  amount  of  pectin  present.  Such  a  jelly,  however,  will  ferment 
or  spoil  through  the  action  of  yeasts  or  molds  unless  sterilized.  At 
least  65  per  cent  of  sugar  must  be  present  to  prevent  spoiling  and 
unless  jelly  contains  this  amount  it  must  be  hermetically  sealed  and 
sterilized  to  preserve  it. 

Ordinarily   one   part   or   one   and   one-fourth   parts   of   sugar   by 
volume  is  added  to  each  part  of  pectin  solution.     This  gives  a  liquid 


pps^1 


Fig.  1. — Jelly  " sheeting''  from  a  spoon  at  jelling  point. 


which  is  considerably  less  than  65  per  cent  sugar.  The  mixture  is 
heated  to  boiling  until  the  excess  water  is  boiled  off  and  in  this  way 
the  sugar  increased  in  the  remaining  liquid  to  any  desired  degree. 
The  boiling  down  also  increases  the  pectin  content  in  the  same  way, 
thus  making  it  more  certain  that  the  liquid  will  jell. 

To  tell  when  the  sugar  has  reached  the  proper  concentration,  due 
to  boiling  down,  most  jelly  makers  use  the  simple  test  of  dipping 
a  spoon  into  the  boiling  liquid  and  allowing  it  to  drip.  If  it  hardens 
or  congeals  in  strips  from  the  lower  edge  of  the  spoon,  it  is  ready  to 
pour  into  glasses.  The  main  fallacy  of  this  test  is  that  it  does  not 
always  indicate  65  per  cent  sugar  and  should  jelling  take  place  very 
much  below  this  degree,  owing  to  a  large  amount  of  pectin,  the  product 
might  spoil.     The  thermometer  test  is  more  reliable.     For  this  test, 


first  heat  water  to  boiling,  insert  a  Fahrenheit  thermometer  and  read 
the  boiling  point.  For  sea  level  points  or  moderate  elevations  this  will 
be  about  211  or  212°  F.  Then  insert  the  thermometer  in  the  boiling 
jelly  solution.  When  it  boils  au  8°  F.  above  the  boiling  point  of  water, 
it  has  reached  the  proper  sugar  concentration.     When  water  boils  at 


Fig.  2. — Sugar  Tester,  Chemical  Thermometer  and  Cylinder  for  deter- 
mining point  at  which  the  jelly  is  sufficiently  concentrated. 

212°  F.,  the  jelly  should  boil  at  220°  F.  Practically  all  large  producers 
of  jelly  use  the  two  methods  in  conjunction.  A  suitable  thermometer 
for  this  purpose  is  one  of  the  form  known  as  "chemical  thermometers" 
registering  up  to  240°  F.  One  sufficiently  accurate  will  cost  75  cents 
to  $1.00. 

A  third  method  is  to  test  the  hot  liquid  with  a  sugar  spindle, 
hydrometer,  "scale,"  or  "tester,"  as  it  is  variously  termed.  The  hot 
solution  is  poured  into  a  tall  tin  or  glass  cylinder  about  fourteen  inches 


by  one  and  one-half  inches  and  the  sugar  hydrometer  inserted.  The 
degree  is  read  off  on  the  scale  at  the  surface  of  the  liquid.  Two 
different  scales  are  in  use  on  sugar  hydrometers,  namely,  the  Brix  and 
Baume  scales.  When  the  boiling  liquid  has  reached  the  proper  con- 
centration for  jelly,  the  Brix  scale  will  read  59°  and  the  Baume  will 
read  32°.  This  means  that  when  the  jelly  cools  down  to  room  tempera- 
ture it  will  show  65°  Brix,  corresponding  to  65  per  cent  sugar.  The 
Brix  hydrometer  is  made  to  give  per  cent  of  sugar  in  solutions  when 
tested  at  63.5°  F.  When  used  in  hot  solutions  near  the  boiling  point, 
the  instrument  gives  a  reading  six  to  eight  per  cent  too  low  owing 
to  the  fact  that  liquids  expand  on  heating.  This  explains  why  59° 
Brix  in  the  hot  juice  corresponds  to  65  per  cent  of  sugar  in  the  cooled 
jelly.  The  Balling  hydrometer  is  practically  the  same  as  the  Brix  and 
can  be  used  just  as  well.  If  a  hydrometer  of  any  kind  is  employed, 
the  exact  meaning  of  the  scale  must  be  understood. 

For  practical  purposes,  the  thermometer  test  will  be  found  most 
reliable  and  convenient. 

Flavor. — The  boiling  of  the  fruit  to  extract  the  pectin  and  the 
boiling  of  the  pectin  and  sugar  solution  drive  off  much  of  the  fruit 
flavor,  and  aroma.  In  order  to  replace  this  lost  flavor,  the  jelly  may  be 
flavored  with  orange  or  lemon  extract  or  oil.  It  should  be  allowed 
to. cool  to  about  175°  F.,  after  it  has  reached  the  jelling  point,  before 
any  flavoring  is  added.  Some  of  the  flavoring  evaporates  if  the  jelly 
is  too  hot  when  it  is  added.  Extracts  or  oils  of  lemon  or  orange  may 
be  obtained  from  grocery  stores  or  the  jelly  may  be  flavored  by  one  of 
the  following  methods.  (1)  Grate  the  yellow  rind  from  two  oranges 
or  two  lemons  fine  on  a  vegetable  grater.  To  the  gratings  add  about 
three  teaspoonsfull  of  water  and  squeeze  the  liquid  from  the  mixture 
through  a  small  cloth  bag.  This  liquid  will  flavor  about  eight  glasses 
of  jelly  when  added  after  the  jelly  has  cooled  to  about  .175°  F.,  in  the 
pot.  (2)  A  more  concentrated  extract  may  be  made  by  adding  one 
ounce  of  pure  grain  alcohol  to  the  gratings  from  two  oranges  or  lemons 
and  allowing  this  to  stand  in  a  covered  glass  over  night.  The  extract 
can  then  be  pressed  from  the  gratings.  Six  to  ten  drops  of  this,  per 
glass,  will  be  sufficient.  If  the  clearness  of  the  jelly  is  not  important, 
it  may  be  flavored  by  adding  a  small  amount  of  grated  dried  peel. 

Bitterness. — Oranges  picked  at  the  beginning  of  the  season  give 
bitter  jelly  and  marmalade.  The  fresh  fruit  is  not  bitter,  but  when 
it  is  boiled  the  bitterness  becomes  apparent.  But  if  the  fruit  is 
used  well  after  the  start  of  the  season,  no  bitterness  will  develop. 
This  is  a  very  important  point  and  must  be  borne  in  mind  when 


6 

making  orange  jelly  or  marmalade.  If  a  little  bitterness  is  desired, 
it  can  be  obtained  by  using  a  little  "grape  fruit"  with  the  ripe  oranges. 

Blending  ivith  Other  Fruits. — The  pectin  solution  from  oranges 
and  lemons  is  more  or  less  neutral  in  flavor  but  is  rich  in  pectin  and 
can  therefore  be  used  to  fortify  juices  of  strawberries,  peaches,  cherries, 
raspberries,  etc.,  which  are  too  weak  in  pectin  to  jell  themselves.  In 
this  way  we  can  make  jellies  with  the  flavors  of  these  various  fruits. 
Blends  can  also  be  made  with  fruits  containing  enough  pectin  of  their 
own  to  give  jellies.  Loganberries  or  currants  have  been  found  to  give 
excellent  jelly  when  blended  with  oranges.  This  may  be  used  as  a 
means  of  increasing  the  quantity  of  jelly  made,  or  of  diluting  the 
acidity  or  flavor  of  the  fruit. 

Jelly  from  Dried  Citrus  Fruits. — Dried  oranges  and  lemons,  when 
soaked  in  water  and  boiled,  give  a  pectin  solution.  Four  to  six  lemons 
to  a  dozen  oranges  is  a  suitable  proportion.  From  this  solution  jelly 
or  marmalade  can  be  made.  This  offers  great  possibilities  for  the  use 
of  dried  orange  and  lemon  culls  in  bakeries  in  place  of  the  dried  apple 
waste  now  used.  The  pectin  solution  from  the  dried  fruit  can  be  used 
as  a  basis  for  large  numbers  of  blended  jellies.  If  sliced  thin,  the  fruit 
dries  very  readily  in  the  sun  or  it  may  be  artificially  dried  in  some 
form  of  fruit  evaporator. 

The  skins  of  oranges  or  lemons  of  which  the  juice  or  pulp  has  been 
used  for  other  purposes  will  serve  as  an  economical  source  of  pectin  for 
domestic  use.  They  may  be  used  directly  or  dried  and  kept  until 
needed.  The  drying  must  be  carefully  done.  If  cut  into  small  pieces 
they  will  dry  in  an  ordinary  dry  room.  If  dried  too  slowly  they  may 
mold,  if  dried  in  an  oven  they  may  be  scorched. 

RECIPES  FOR  JELLY 

By  following  the  definite  directions  given  in  the  following  recipes, 
satisfactory  jellies  should  result.  These  recipes  are  the  results  of 
experiments  and  have  been  thoroughly  tested. 

Orange-Lemon  Jelly  Number  One. — Select  six  thoroughly  ripe  or- 
anges and  three  lemons.  Cut  the  whole  fruit  (including  whole  skins) 
into  slices  about  one-fourth  of  an  inch  thick.  Cover  with  water  and 
boil  slowly  adding  water  occasionally  to  replace  that  boiled  off.  At 
the  end  of  an  hour  the  fruit  should  be  soft,  but  not  "mushy"  and 
the  liquid  clear.  Strain  the  hot  juice  through  a  coarse  bag  without 
pressure  and  place  it  in  jars  or  bottles  to  settle.  Press  out  the  remain- 
ing liquid  from  pulp  and  set  aside  to  settle.  After  twenty-four  hours, 
pour  or  siphon   off  the  clear  liquid.     The  sediment  may   be  filtered 


through  a  jelly  bag  or  thrown  away.  To  each  pint  of  liquid  add  one 
and  one-fourth  pints  of  sugar.  Boil  with  frequent  skimming  until  it 
reaches  8°  F.  above  the  boiling  point  of  water,  or  until  the  liquid  will 
''sheet"  from  a  spoon.  Allow  to  cool  to  about  175°  F.  Add  a  little 
orange  extract  to  flavor.  Pour  into  glasses.  Cover  with  a  thin  layer 
of  melted  paraffin. 

Orange-Lemon  Jelly  Number  Two* — Use  six  oranges  and  three 
lemons.  This  will  give  eight  glasses  of  jelly.  Remove  and  discard 
the  thin  outer  layer  of  the  rinds,  leaving  the  white  portion  on  the  fruit. 
Remove  the  white.  Tie  this  in  a  close  mesh  bag.  Shred  the  pulp  very 
fine.  Add  three  times  its  bulk  of  water.  Boil  hard  forty-five  minutes 
with  the  bag  of  white  rind  immersed  in  the  liquid.  This  furnishes 
the  pectin.  Skim  frequently.  Remove  the  bag  and  throw  the  contents 
away.  Strain  off  the  clear  liquid  and  let  stand  twenty-four  hours. 
Carefully  siphon  or  pour  off  the  clear  liquid  and  boil  ten  minutes. 
Add  an  equal  quantity  of  sugar  and  boil  till  it  jells  (about  five 
minutes).  When  the  liquid  "sheets"  from  a  spoon  it  is  ready  to  jell. 
A  clear  amber  colored  jelly  will  result  from  use  of  this  recipe. 

Those  who  do  not  object  to  the  flavor  of  the  yellow  portion  of  the 
rind  may  leave  it  on.  The  sediment  from  the  settled  juice  will  also 
make  jelly  but  it  will  be  cloudy. 

Grape  Fruit-Lemon  Jelly. — By  substituting  grape  fruit  for  oranges 
in  the  above  recipes,  a  clear  bitter  jelly  can  be  made. 

Lemon  Jelly.— Cut  the  lemons  in  half  and  press  out  the  juice. 
Cut  the  pulp  and  rinds  into  small  pieces.  Return  about  one-third  of 
the  juice  to  the  pulp  and  rinds.  Cover  with  water  and  boil  one  hour, 
replacing  the  water  that  boils  off.  Press  out  the  hot  juice  and  proceed 
as  in  orange  jelly  recipe  number  one  above.  (The  two-thirds  of  lemon 
juice  rejected  can  be  used  for  other  purposes.) 

Marmalades. — Most  housewives  make  the  mistake  of  leaving  too 
much  pulp  and  peel  in  their  marmalade,  giving  it  the  appearance  of 
jam  rather  than  of  marmalade.  A  marmalade  should  be  a  clear  jelly 
with  a  few  thin  slices  of  peel  suspended  in  it.  The  peel  in  the  mar- 
malade should  be  tender  and  should  be  well  distributed  and  not  all 
floating  at  the  surface.  This  requires  preliminary  boiling  of  the 
thinly  sliced  skins  to  soften  them  and  a  second  long  boiling  with  the 
sugar  and  juice  so  that  the  syrup  will  penetrate  and  make  peels  and 
jelly  of  the  same  specific  gravity  or  density.  The  following  recipe 
conforms  to  these  principles: 


*  Furnished  by  Miss  Elliot  of  Domestic  Science  Department,  Covina  High 
School. 


8 

Orange-Lemon  Marmalade. — Use  six  oranges  and  three  lemons. 
Cut  four  of  the  oranges  and  the  three  lemons  into  slices  about  one- 
fourth  of  an  inch  thick.  Cover  with  water.  Boil  about  one  hour, 
replacing  occasionally  during  the  boiling  process  the  water  that  boils 
off.  Drain  and  press  out  the  hot  juice  through  a  coarse  mesh-bag  and 
place  in  jars  or  bottles  to  settle.  Slice  the  remaining  two  oranges 
into  very  thin  shavings  or  slices.  Cover  with  a  small  amount  of  water 
and  boil  until  tender.  Mix  the  hot  juice  thus  obtained  in  jars  or 
bottles  with  the  juice  from  the  first  oranges  and  lemons.  Do  not 
press  the  boiled  slices,  but  wash  most  of  adhering  pulp  from  the  skins 
under  a  good  jet  of  water  from  a  faucet.  Drain  off  the  water  and 
set  the  peels  aside  until  the  next  day.  After  twenty-four  hours,  pour 
or  siphon  off  the  clear  juice  set  aside  to  settle  in  the  bottles  on  the 
previous  day.  Add  the  boiled  and  washed  thinly  sliced  peels  from  the 
two  oranges  to  the  clear  juice.  To  each  part  of  liquid  and  peels  add 
one  part  of  sugar.  Heat  with  frequent  skimming  until  the  marmalade 
boils  at  8°  F.  above  the  boiling  point  of  water  or  until  it  sheets  readily 
from  a  spoon.    Pour  into  glasses  and  cover  with  paraffin. 

Grape  Fruit-Lemon  Marmalade. — Proceed  exactly  as  above  except 
that  pomelos  are  substituted  for  the  oranges. 

Grape  Fruit-Orange-Lemon  Marmalade. — Proceed  as  with  orange 
marmalade  using  three  pomelos,  three  oranges,  and  three  lemons.  The 
pomelos  give  a  bitter  taste  and  a  marmalade  resembling  more  or  less 
the  bitter  English  marmalade.  The  process  is  the  same  as  for  orange 
marmalade,  including  the  use  of  two  of  the  oranges  to  thicken. 

Quantities  Needed  for  Ten  Gallons  of  Jelly 


Weight  of  Fruit,  in  lbs. 

Gallons  of 

A 

Pounds 

Sugar 
added 

Water 
added 

Cloudy 

juice 

obtained 

Clear 

juice 

obtained 

Yield  of  Jelly 

Oranges      Lemons      Pomelos 

Gallons      6-oz,  glasses 

1 

68             17 

15 

11 

9 

90 

10             270 

2 

12             58 

15 

11 

9 

90 

10             270 

3 

75 

17.5 

11 

9 

95 

10             270 

The  figures  in  the  above  table  were  obtained  from  small  scale 
experiments  but  represent  approximately  the  probable  yield  on  a 
larger  scale.  Fruit  of  medium  size  was  used  and  in  the  proportions 
given  in  the  recipes  i.e.,  for  orange-lemon  jelly,  six  oranges  and  three 
lemons;  for  pomelo-lemon  jelly,  six  pomelos  and  three  lemons;  and 
for  lemon  jelly,  twelve  lemons  less  two-thirds  of  their  juice. 


